www.ruidp.gov.in

: Government of Rajasthan

Office of Project Directornajasthan Urban Infrastructure Development Project

AVS Building, Jawahar Circle, JLN Marg, Jaipur -302017

Tel No.: 0141-2721966, Fax No.: 0141-2721919, email : mail@ruidp.gov.in, web site: '

F3 (106) (32)/RUSDIP/PMU/CMS/2007/1Cf,z;2-3 Dated:J1.03.2008

Sub:Ref:

Design & Construction Management System: Circular -8.General guide lines for Drainage Sector work to be taken underRUSDIP.

The importar1ce of adequate & efficient drainage to the structural integrity of othersector is well recognized as such it is to be planned in phased manner and with thisview major short, medium & long term intervention are proposed in the fifteentowns under RUSDIP. Following are the common guidelines to be followed whiledeveloping drainage strategies for RUSDIP:-

( :..

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1

System Design & Preparation of Master Plan

~ Any drainage plan for a RUSDIP city must begin with describing its physical &administrative dimensions, its population the ecology & its economic frame workof particular importance, a full description of the flood prone areas, includingdepth of floods, their frequency, and the number of hours or days the area isflooded within a particular time period, history of past floods, topographic /contour etc. The flood prone areas should be clearly marked on the city map.The availability of water supply and the means of discharging wastewater andsurface drainage, the slope and contours of the land, the rainfall characteristics,and subsoil characteristics are the principal elements of consideration. Inaddition, environmental impact of the drainage system and the planned landdevelopment should be taken in account. A description analysis of the generaltopography, soils and physical features such as wooded areas, agricultural land,waterways, water bodies, flood plain areas, storage ponds, roads, politicalboundaries, and other existing infrastructure that may affect the generalappearance and future use of drainage system, their modification with possiblealternatives which will be technically, economically & environmentally viableSelection and description of final discharge / outfall point will be necessary.-

2) The drainage plan of city must provide the means to accommodate future needsand likely changes in the city in next 30 years i.e. upto design year 2041 & planfor them which may not be clearly defined now. At the same time, it must besufficiently practical to be adopted today, and must be financially feasible underpresent circumstances. The City's Master Development Plans must be taken intofull consideration, and the report should explain how the drainage plan willaccommodate the future growth of the city.

The survey of existing drainage system with their, width, depth, length andslopes should be done and their capacity should be determined. Drainage zonesto be delineated for both the existing drainage system and proposed drainagesystem based on the contours.

The drainage report should contain maps a~; well as a written description of theland use of the general area. The report should clearly show, by appropriatemaps the assignment of land to residential, commercial, industrial, and public

3)

Circular-8 Guideline Page I ofGr Draina!!e sector

lands, etc. It need not to gointentions.

lto

great detail but should illustrate the designer's

4) Records of rainfall, stream flows, reservoir levels, and other pertinent data suchas major reasons for the failure & deficiencies of existing storm water drainsshould be obtained from the relevant agency. The raw data may be included in

appendices.

5) Consideration must be given to the previous studies and expert opinionregarding the economic aspects of the areas, Census data, past populationdata, and estimates of the probable future developments and changes in landuse. The report should describe social characteristics of the area that affect thelocation and number of facilities used to serve the population.

6) A matter to be investigated and thoroughly studied during the concept anddetailed design stages is the provision of adequate facilities for handling thestorm water runoff. Topographic maps will be useful for preliminary planning,while detailed topographic survey (longitudinal surveys and cross sections),levels of the city area in a grid are an essential prerequisite for final design.Natural channels usually provide the most economic means for conveyingsurface drainage, but the quantity of water to be conveyed, existing featuresand constraints, and improvement costs are the main considerations whenchoosing between a closed conduit or an open channel.

7) The proper assessment & condItions of sub surface utilities, strata & water arevery important for the execution of drainage system. This should be ensuredbefore designing of the system & needs to be properly quantified. Accordinglyprovisions should be taken in the estimates & BOQ.

8 It is desirable to start the design considering the levels at the outfall of drainagelocations of drainage system so that the level and bed slopes of the drains arefixed accordingly as per outfall to allow discharge to pass using gravity flow.While in the most cases, it would be possible to drain out the water usinggravity flow, in some location pumping may be necessary and should becritically examined to avoid it with various other alternatives. Some of theimportant locations where special attention required are:

a. Underpasses & Subwaysb. Rotariesc. Fly over & bridgesd. Medians

9) Natural features such as rivers and streams, ridges, troughs, woodlands, watercourses, ponds and lakes, wetlands, etc., should be utilized to as great a degreeas possible to convey the storm water flows and/or retard the rate of runoff andminimize the design discharge. Logs of test wells and producing wells might beavailable with data such as strata of soils, elevation of groundwater, andlocation of rock. Locations of unfavorable subsurface conditions should beclearly shown. Where existing information is not available for the area, it isessential that subsurface investigations be completed before the final design.Rock at a shallow depth must be considered for the drainage plan. A water tableclose to the surface could be of great significance to the designer and should bementioned if applicable.

Palcular-8 Guideline Dr Drainage sectl

10) Structural interventions should be designed with simplicity and .ease ofmaintenance topmost in mind, and complementary non-structural interventionsshould be recommended in the reports. Examples of these are solid waste

management improvements, removing encroachments, public awarenesscampaigns, improved operation and maintenance procedures, introducingbuilding controls for flood prone areas, and preservation of ponds, water bodiesand wetlands.

It is generally not possible to take up work for the whole city at a time and thework may have to be prioritized. A method of prioritizing can be:

(a) Areas where lack of a drainage system is creating unhygienic livingc;:onditions or unacceptable odor levels, e.g. areas with a highpopulation density and no drainage system.

(b) Areas where the quality of the ground water is adversely affected bypermeable storm water and the ground water is a source of drinkingwater.

(c) City centre, commercial centre and the more densely populated areasof the town.

(d) Flood prone roads and areas.

~The drainage report should delineate the various catchment areas on thecontour map !at an appropriate scale. The catchment area map should indicatethe main features to be used for the design and should include such item ascatchment area sizes, topography, channel slopes, land use and respectiverunoff coefficient, design rainfall frequency and intensity, design channel flows,location of major structures (existing and planned), critical elevations, floodprone areas etc.

13) General Considerations in Design of Storm Water Drain:

(a)

(b)

..

(c)

Cd)

(e)

(f)(9)

Drain should be planned taking into consideration the ground levels,slope of the ground, valley and ridges and also the land uses plannedfor urban development.Drains should be planned to get good longitudinal slope, consideringthe nature of soil, water level. Drainage of large area can be betterachieved by subdividing it into small grids to avoid a long main drain.Aim should be to get a higher velocity for the dominant flow.Efficiency in maintenance of drainage system should be an importantconsideration in selecting the size, (covered or open) shape and thelocation. The specification of the drain should also aim at preventingthe possibility of ingress of other extraneous materials, debris, rubbish,vegetation etc. Where gratings are provided on drains, they should solocated as to attract attention of maintenance staff, easy to approachinspect and clean it.An attempt shall be made in the design to provide higher starting andhigher outfall bed levels in drains. A free outfall shall be attempted asfar as possible.Design of main drain shall be so made as to allow use of normalmethods for desilting operation.Inlets to the drains to be properly designed and located.It is always desirable that run off from the catchment areas outside thecity boundary should be taken by suitable drain layout to bypass the

township.

Page 3 of 17Circular-8 Guidelines tor Drainage sector

(h) The design flow will be the runoff from rainfall only,wastewater of the community will be taken into account.

No other

Management and Maintenance of the Drainage Systems:4)

The capital cost involved in construction of drain forms a small component ofthe total expenditure involved in providing the infrastructure in the form ofcarriageway, footpath, medians, street light and other street furniture. Like anyother capital asset, storm water drainage system also needs constantmaintenance, if the investment is to serve the purpose it is meant for. The needfor a good storm water drainage or absence of it is felt by many only duringcertain days of the year.

15)

t

The drainage system is at its best when it is maintained as properly asdesigned. For this purpose it is necessary that drains keep their shapes andslope in designed manner during their life time. It is also necessary to ensurethat the drains retain their full cross section, particularly for the monsoon. Thesystem of maintenance can be classified into following three categories:

a) Continuous regular maintenance

b) Periodical maintenance

c) Special maintenance/ Repair for improvement

The extents of these repairs depend upon size of the drain, location of thedrain, nature of habitation nearby and cross drainage structures. The difficultyin maintenances is also caused by a lesser degree of consciousness/ civic sense.Malba, garbage, solid waste and road cleanings enter the drain resulting insilting and solid crustation of extraneous material making the maintenancedifficult and poor efficiency of drains. Inlet of Drains to be maintained properlyfor the entry of storm runoff. A broad check list is given in Appendix A-3 of IRC-SP-SO may be referred to which by no means is exhaustive.

8

Periodical inspection and maintenance of drains is very necessary as failure ofdrains may occur due to deficiency in maintenance rather than defect in design.The principal activities may be:

a) De-silting;b) Cleaning of weeds;

c) Cleaning of obstruction, debris and blockage;

d) Repairing of lining immediately at the commencement of damage ordeterioration.

Continuous action and attention to detail are important aspects pertaining tomaintenance programmers. It is very essential that maintenance unit have allthe drawings of existing drains showing all technical details on ground. Thedrain should be identified by suitable numbering with proper chainage. It shouldbe the Endeavour to ensure that works are maintained as per details shown ininventory prepared just after completion of the drainage scheme.

The cleaning routine should indicate clearly the work to be done, the frequencyfor that work, the equipment and labour to be used and most important anysafety measure and equipment required. Though, it is not practicable to assignindividual frequencies for each element as a routine for each area, it should be

18)

'ircular-8 Guidelines for Draina!!e sector Page 4 of

such to ensure that various elements are cleaned before the drain gets blockedFor different localities, it may have to be based on local experience.

It is common practice that all drains are de-silted thoroughly before on set ofmonsoon. All kutcha side drains dressing and deepening before monsoon. It isalso essential that all drains are in a state of repair and the works of re-grading,reshaping, or profile correction wherever required is completed well before theonset of monsoon.

During the rains also, a watch should be kept at the exit and entry point forwater for the presence of undesirable collection of rubbish, polythene, paperbags blocking the passage of water and in everyway ensuring free unobstructedflow of rain water. During rains specially after heavy showers all cross drainagestructure should be inspected to observe any blockage due to debris, log ofwood and other such materials. A watch on the deficiencies in the drainagesystem should be kept and problem locations identified and record kept.Necessary corrective measures should be adopted immediately after rains. Awatch on missing manhole covers and broken covers is also required to be keptand replacement/repairs carried out on priority to avoid accidents.

Design Criteria

The design of drainage system should generally follow the guidelinesrecommended in Indian Road Congress, CPHEEO manual on Sewerage andSewage Treatment or other relevant codes with proper justification for deviationor modification if any and should involve:

y" Calculating the total discharge that the system will require to drain off.y" Fixing the slope & dimensions of the drain to have adequate capacity to

carry the discharge and afford proper maintenance.

The discharge is dependent upon intensity and duration of precipitationcharacteristic of the area and the time required for such flow to reach the drain.The storm water flow for this purpose may be determined by using the rationalmethod, hydrograph method, rainfall run off correlation studies, digitalcomputer models and empirical formulae. The empirical formulae that areavailable for estimating the storm water run off can be used only whencomparable conditions to those for which the equations are derived initially canbe assured of the different methods available, rational method is mostcommonly used and serves the purpose for design of drain satisfactorily.

The cost of any drainage structure depends on its size, which depends heavilyon the return period adopted by the designer. This, in turn, depends on thelevel of protection that is deemed to be adequate for reducing the potentialcosts of flood damages and minimizing inconvenience to the public. As such, thedecision on what return period to adopt for design purposes is the result of aninformal cost/benefit analysis -where the potential for damages is low or costsare small a short design return period is usually considered adequate, butwhere the potential for damages is high or where failure would endangerexpensive property, then a longer (more conservative) return period is selected.

Typical design return periods, which are recommended to be used for differenttypes of urban areas are provided below. The drainage report should justify anyamendment to these values.

:ircular-8 Guideline: or Drainage sector Page 5 0

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Area Characteristics

Low valued and residential areas

Higher valued commercial/industrial areas

Critical areas: significant potential for damage/inconvenience

Major culverts, bridges, etc. for National and State Highway

Dams, reservoirs, etc., ,

Most RUSDIP city areas may adopt a design return period of 1-2 yeas. CPHEEOmanual is desired to be followed. Likewise, for most of the culvert and bridgereturn periods will be 25 and 50 years, respectively. The DSC may modify theseparticular design return periods if, in the DSC's best professional judgment, thelocal conditions justify it.

25) Based on the practice being followed in metropolitan cities in our country & costconsideration in mind, it is recommended that a return period of 1 to 2 years beadopted for estimation of runoff.

,

Time of Concentration: -It is the time required for the maximum run off rate todevelop. It is equal to time required for a drop of water to run from the mostremote point of the catchment area to the point for which the run off is beingestimated. Empirical formula (IRC-SP:50) may be used to determine the timeof concentration.

tc = (0.87) (L 3)°.385

(H)Wheretc = Time of concentration in hoursL = Distance of critical point to the drain in KmH = fall in level from the critical point to the drain level in meters.

(for details ref: IRC: SP: -50 -1999 page 12& 13)

Rainfall Intensity: -It has been observed that shorter the duration of criticalrainfall, the greater would be the expected average intensity during that period.For example, during a 30 minute rainfall, some 5 minute period, or any periodless than 30 minute, will have an average rainfall intensity greater than of thewhole storm. The critical duration of rainfall will be which produces maximumrunoff. This duration is equal to the time of concentration, since shorter periodsdo not allow the whole area to contribute water, and longer duration will givesmaller average rainfall intensity. The problem thus reduces to one ofestablishing a relationship between time of rainfall duration and probable orexpected rainfall intensity. For design purpose high intensities are of

importance.

The rainfall intensity (I) in mm/hr will depend on design return period (stormfrequency) selected by the designer I and on the time of concentration (tc) forthe storm water flow to reach the section being designed. Initial inlet times mayrange from 5 minutes for a steep slope on an impervious to 30 minutes for aslightly sloped city street; usually an initial inlet time of 5 to 10 minute isassumed for design purpose.

9) It is also added that as per practice being followed in most of the metropolitancities, the calculation of runoff is being carried out using hourly rainfall intensityfor a return period of one to two years. This is primarily for simplicity of

Circu1ar-8 Guidelines for Drainage sector Page 6 of 17

calculation. However I for a large drainage system, it is recommended thatcalculations be carried out on the basis of detailed analysis as the efforts mayworth the savings in cost.

The designer will need to develop .rainfall intensity-duration curves that areappropriate for each city, based on historical rainfall data, and use them fordetermining the appropriate rainfall intensity (I) for use in the critical rationalformula. To do this, historical rainfall records covering several years will need tobe obtained. The rainfall data may be obtained from the MeteorologicalDepartment, Government of India. For RUSDIP we suggest minimum period of15 years, including at least one year with a major flooding event. From theserecords, rainfall intensities are to be computed corresponding to storms of1,2/5,10 ,25,50 and 100 year frequencies and corresponding intensity durationcurves can be developed.

Appendix 1 gives an example calculation of rainfall intensities for variousdurations by return period. Comparative rainfall intensity curves (intensity (I)in mmlhr vIs time of concentration in minutes) for different return periodsshould be developed and presented as a figure as mentioned in (30).

Rational Formula for Estimating Peak Run Off Rates

For small water sheds not exceeding 50 km2, as in the usual case for urbandrainage system, the rational method is widely used for estimating the peakrun off rates. The formula is

Q=O.O28 PAlc

Where,Q= Design peak run off rate in cumjsecP= Coefficient of run off for catchments characteristicsA= Area of catchments in hectaresIc= Critical intensity of rainfall in cm per hour (corresponding to the

design time of concentration (T) in hour and return period selected)

For the catchment areas exceeding 50 km2, Bell's formula should be used forworking out of the rainfall intensity and accordingly the design discharge.

The best possible estimation of peak run off rate is possible where the gaugerecords of rainfall are available from the automatic rain gauge recorder. Anexample for the same is presented in Appendix 1.

If only maximum day rainfall is collected, the intensity of rainfall in cmjhr canbe calculated as follows (IRC: SP -13 -2004 Page 8 -11)

Ic F / T (T + 1 / t + 1

In which,F = total precipitationT = duration of the rainfallIc = is the intensity of rainfall for a duration of t (time of concentration)

The coefficient of run-off (C) is the portion of precipitation that makes its way tothe drain. Its value depends on a large number of factors such as permeability

-R Guidelin for Oraina!!e se 'aile 7 of

of the surface, type of ground cover, shape and size of catchments area, thetopography, geography, initial state of wetness and duration of storm. Thevalue of 'c' commonly adopted for used in Rational Formula is given in Table:-

Table -Values of Co-efficient of Run-off

If any change is expected in the land use pattern in the contributing area duringthe life time of the drainage system, consideration for same should also betaken in the design. It is a common practice that the run-off coefficient for thewhole area is derived after estimating or ascertaining the proportion of thevarious surface to the whole area. Some common figures adopted for coefficientof run-off are given in Table below. It is also to be remembered that run-offcoefficient tends to become larger as rain fall continues due to filling ofdepressions in impervious surfaces and soaking of the upper layer of exposedsoil.

Table -Co-efficient of Run-off for Various Surfaces

!

51. No. Description of surface Coefficient of Run offI Most densely built UD areas 10.7 to 0.9I For adioininq area to built UP areas 10.5 to 0.7I Residential areas 10.25 to 0.5I Sub-urban areas with few buildina ! 0.10 to 0.25

36) Hydraulic Design

Design of Drain Section:Capacity of the drain is normally designed using Manning's formula

Q= (1/n) A R2/3 S1/2And

V= I/n R 2/3 S 1/2

WhereQ = discharge in cumjsecV = Mean velocity in mjsecn = Manning's rugosity coefficientR = Hydraulic mean radius which is area of flow cross section divided by

wetted perimeter.5 = Gradient of drain bedA = Area of flow cross section in m2

The coefficient of rugosity for various surfaces given in IRC:SP:42 may bereferred. Some average values are however indicated in table for ,general

guidance:

Page 8 of 17Circular-8 Guidelines tor Drainage sector

38) a) Velocities

Suitable judgment has to be made to use maximum velocities to ensure asection of drain which will pass through a narrow road width.

The designer may select any internationally accepted design standard foropen channel flow as well as for retention basins, flow control structures,culverts, drops, manholes, and other hydraulic structures, but must clearlystate what these are and justify them. We recommend that the Manning'sFormula be used for calculating the velocity of flow (and discharge) in openchannels; [See Section (36)]

To ensure self cleaning of the drain, a minimum velocity of 1.5 m per secondmay be desirable, which may require installation of concrete drains or paveddrains. In urban drainage maximum velocity should be tried to be achieved tohave minimum cross section of the drain keeping in mind the limitedavailability of space on the road sides and should be paved to consider thesame. The max velocity may be considered to the extent of allowable velocityto prevent erosion as detailed in IRC-SP-42 table 6 which mentions up to6mjsec in cases of rock surfaces and paved drains.

b) Free Board: Generally adopted free board is as follows:

In RUSDIP, in the design free board should be avoided.

Circular-8 Guidelines for Drainage sector Page90f17

c) Minimum section of drain: It should be possible to clean the drainperiodically using a spade. Accordingly, it is recommended thatminimum width of a drain should not be less than 250 mm. In case ofpipe the minimum diameter should not be less than 450 mm.

d) The effective section of the drain carrying design discharge should beconsidered below the bell mouth pipe so that there is no back flow ofwater on to the road.

39) Channel Shapes: The usual channel shapes are:i) Parabolicii) Trapezoidaliii) Rectangulariv) Triangular or V shaped

The parabolic profile is considered to be best for hydraulic flow but its actualconstruction and maintenance is difficult. The V shaped drain is not very popularin urban areas as its de-silting is difficult. The trapezoidal and rectangularsections are easy to construct and are considered most suitable. In urban areasall drains passing through built up area and near to bus stand, crossing etcshould preferably be covered so that the drains are not used as dust -bins.Even if drains cannot be covered in the initial stage due to economy reasonsprovision should be available for covering it at a later stage. However, it shouldbe kept in mind that pipe drains are difficult to de-silt and maintain.

Economical sections (for lined drains)As far as possible, for obtaining economical sections the relation between bedwidth and depth shall be as follows:

i) Rectangular drain b=2dii) Trapezoidal b= 0.82 d (1: 1 side slope)

b= 1.24 d (1/2: 1 side slope)For main or trunk drains the side slopes should be 1: 1 or 1/2: 1 depending uponnature of soil and availability of land.

41 Silt Pit: A silt pit shall be constructed at all the inlet points of every covereddrain and also provided with vertical grating in order to avert entry of floatingmaterial into the drain.

Drainage over surface: All surface water is initially drained over the surfacebefore it is collected in the drainage system. The drains are located along roadside and the water is let into the drain through gulleys, bell mouths or othersuch water entrances. Minor roads in residential areas are narrow and it may bedifficult to provide separate space for drains. In such cases the water can beallowed to flow in kerb channel which can be led into the main drainage systemwhere the minor street meets the main road. Beside saving in the cost of drainthe water is kept at higher level which may help either in reducing the depth ofdrain at downstream or provide a better gradient and reduce silting and othermaintenance problems. Another advantage is that the water takes longer toenter the drain and reduce the peak flow.

Drainage through open channel: The open drains along the road sidedefinitely have to be away from the shoulders or the berm and requireadditional space. They are easier to maintain and allow removal of silt and othersolids easily. Also, for a given cross section open drain can carry much largerdischarge particularly in flood conditions when the drain is surcharged.

Circular-8 Guidelines for Drainage sector Page 100f17

However, open drains have their inherent disadvantage of being used as a dust-bin. Due to this reason their hydraulic capacity for most part of the yearremains poor.

44) Covered drains or pipe: Covered drain i.e. rectangular drain with cover slabsare free from garbage dumping problems. Also, they can be located below thefootpath or in extreme cases below the carriageway where space is restricted.The closed system, in many cases, is demanded by residents of the adjoiningarea. Pipe drains also have the above advantage but they should be used forsmall lengths as cleaning of such drains is not possible by ordinary method andthey need special equipment. Also due to minimum size requirement andcushion requirement, such drains tend to become deep and increase the depthof drain at the downstream end. Pipe lines should be preferred in cases of steepslopes up to 900 mm dia to 1200 mm.

45) Manholes Ordinary manholes &. Spacing: A manhole is an openingconstructed on the alignment of a covered or pipe drain for facilitating a personaccess to it for the purpose of inspection, testing, cleaning and removal ofobstructions from the drain. The spacing of manhole depends upon the natureof drain and the cleaning devise likely to be used. Generally manhole in straightreaches is at a spacing of 50 to 100 m or so.

Maintenance of the Drainage system:

Adequate arrangements should be considered for maintaining the drainagesystem for proper flow condition.

8

General:.,/' The surface drains should not be connected to the sewer systems as they

also carry rain water, solid wastes and silt which tend to choke thesewers.

.,/' During construction full care needs to be taken for diverting traffic and for

fencing and safety of the excavation sites. The excavated materials mayhave to be transported to other suitable sites (to maintain flow of traffic)and transported back for refilling of trenches. The provisions for properlysupporting the trenches should be taken.

.,/' The issues related to safety, excavation in different strata, undergroundwater conditions, shifting of under ground utilities, on site testing,backfilling of trenches, road restoration should be properly attended in thetechnical specifications, estimates and BOQ.

.,/' The standard bidding document should be understood very clearly andshould ensure required details (i.e. special conditions of the Contract,Technical specifications, drawings and BOQ items including preamble toBOQ etc.) for a particular sub-project and there should be harmony in thedocuments prepared by the DSC/IPIU /IPMC/ in-charge packages in PMU.

.,/' The estimates should be reflective of the present market prices and shouldbe based on the current SOR to be issued by RUSDIP and the marketprices for items not included there.

.,/' Safety aspects needs to be attended in the design of the system andincluded in Bid Documents properly -Excavation in deep trenches,barricading, crossing with water supply lines, execution in narrow streets

Circular-8 Guidelines for Drainage sector Page II of 17

Design Report Format:

vi' The report should consist two parts:

(a) City status report

(b) Sub-project specific reportvi' The city status report should contain at least the following chapters:

(a) Index(b) Salient Features of the town -Topography, Hydrology, Geology,

and Ground Strata Existing drainage, Rainfall history, floodprone areas with respect to the designed depths etc.

(c) Introduction -History of drainage schemes with up to datedetails, ongoing & future plans and their status;

(d) Analysis of deficiency in the town with present requirements andfuture requirements of Year 2021, 2031 and 2041, measures tomitigate the deficiencies with improvement in the existingsystem and

(e) Executive summary for suggestive measures to mitigatedeficiencies j long term solutions and list of proposed works in

totality.(f) Phasing of the proposed works in line with allocations under

RUSDIP for fulfilling its goal matrix and indicators. Identificationof works to be taken up by the concerned line agency. Definerole of RUSDIPjULBj others to meet out the deficiencies.

,(' The sub-project specific report should contain at least the following

chapters:(a) Index(b) Introduction -Analysis of Priority for RUSDIP(c) Detail analysis of the sub-project specific requirement and

justification.(d) Sub-project specific present level of indicators and indicators

after execution of the project covering:

General:

,I'

,I',I',I'

Increase in coverage of drainage system and its maintenanceReduction in pollution and use of effluentImprovement in sanitation facilityCorresponding health benefits

Technical Report will contain -narrative of the various design aspect,parameters, alternatives and conclusions -highlighting special features; WorkProgram; Operation and Maintenance; Benefits expected from the investment.

a) Bidding document -Incorporation of Scope of work, specialconditions of contract, Technical specifications, Tender & DetailedConstruction Drawings, Estimate & Bill of quantities and preamble toBOQ etc. in Standard Bidding document.

b) Operation and maintenance -Expectations from the line agency(personal requirement / cost requirement), Expectations from thecontracting firm.

c) Execution Methodology -Sequence of execution, Tentative workplan, interface with other works, Quality Assurance and QualityControl, Safety aspect during execution.

Circular-8 Guidelines for Drainage sector Page 12 of 17

d)e)

f)

g)

Time line for completion of sub-project.

Likely Impact after the completion of sub-project under RUSDIP-Improvement in sanitation facility, reduction in pollution, no. ofbeneficiaries/ colonies covered/ houses & %of total city area,

Linkage of existing and proposed work on base maps prepared byRUSDIP (Availability of plans/ details of existing system)

Sub -project Issuesi. Status of land availability / Land acquisition for structures

ii. Inter departmental issues with Forest, Railways for crossings ofRailway lines and works through railway land, National Highwaysfor road cutting / crossings and Bridges, Power availability fromVVN L,

iii. BSNL, Pollution Control Board, License from explosivedepartment, Removal of encroachment and their resettlement.

iv. Time line for clearance from concerned department

v. Shifting of under ground utilities (sub-project wise) -Details ofconcerned department, Mode of shifting, Clearance from lineagency, Likely impact of shifting

vi. Deposit works to be executed by other departments forexecution of the sub-project.

This circular should be abided by all members of PMU, IPIU, IPMC & O",C.~-- "'- \,.

\6$

c\

DirectorDated: 2.-1-:-03.2008

4.5.

6.

7.8.

9.

Page 13 oft7Circular-8 Guidelines for Drainage sector

Copy to following for information and necessary action:1. Addl. PD -I & III FAI SE (D-I)I Dy. PD (T)I Dy. PD (Adm.)1 SE (WW)I SE(R&B)I

SE (Mon) I PO (all)1 Sr. AO I All APOs I AAOI PA to PD PMU, RUIDP, Jaipur.2. SE PIU, Ajmer, Bikaner, Kota, Jaipur, Jodhpur and Udaipur.3. Executive Engineer/APO's, IPIU, RUSDIP (Concerned), Alwar, Baran-Chhabra,

Barmer, Bharatpur, Bundi, Chittorgarh, Churu, Dhaulpur, Jaisalmer, Jhalawar-Jhalarapatan, Karauli, Nagaur, Rajsamand, Sawai Madhopur and SikarTeam Leader PMCI Team Leader CTA Consultant, RUSDIP.Team Leader, RUSDIP, DSC- I, Bharatpur, DSC- II, Nagaur, DSC- III, Jhalawar,RUSDIP.Dy. Team Leader, RUSDIP, DSC-I, Alwarl Dholpurl Karaulil Sawai Madhopur,RUSDIP.Dy. Team Leader, RUSDIP, DSC-II, Churul Jaisalmerl Barmerl SikarDy. Team Leader, RUSDIP, DSC- III, Chittorgarhl I Rajsamandl Bundil Baran,RUSDIP.ACP, PMU, RUIDP, Jaipur to send bye-mail and put up the Guidelines on thewebsite. f(lzl;.:;1 --

Dy. ~;;ject Director (T)

APPENDIX -I

INTENSITY OF PRECIPITATION

The intensity of rainfall decreases with duration. Analysis of the observed data onintensity duration of rainfall of past records over a period of years in the area isnecessary to arrive at a fair estimate of intensity-duration for given frequencies. Thelonger the record available, the more dependable is the forecast. In Indian conditions,intensity of rainfall adopted in design is usually in the range of 12mm/hr to 20mm/hr.

Table 1.1 gives the analysis of the frequency of storms of stated intensities and durationsduring 26 years for which rainfall data were available for a given town.

TABLE 1.1

8

1 ANALYSIS OF FREQUENCY OF STORMS

.

The stepped line indicates the location of the storm occurring once in 2 years, i.e. 13times in 26 years. The time-intensity values for this frequency are obtained byinterpolation and given in Table 1.2

Table 1.2TIME INTENSITY VALUES OF STORMS

I (mm/hr) t (min)

30354045506075

51.6743.7536.4828.5718.5014.628.12

The relationship may be expressed by a suitable mathematical formula, several forms ofwhich are available. The following two equations are commonly used:

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(i)(ii)

i= a / (t)

I=a/(t+b)

Where,i = intensity of rainfall (mm/hr)t = duration of storm (minute) and

a, band n are constants,

The available data on I and t are plotted and the values of the intensity (i) can thenbe determined for any given time of concentration, (tc) (Fig. 1.1)

Figure 1.1

18 Intensitymm/hr

DURATION (mins.

1.2 Time of Concentration

It is the time required for the rain water to flow over the ground surface from the extremepoint of the drainage basin and reach the point under consideration. Time ofconcentration (tc) is equal to inlet time (t1) plus the time of flow in the drain (t2). The inlettime is dependent on the distance of the farthest point in the drainage basis to the inletpoint, the shape, characteristics and topography of the basin and may generally veryfrom 5 to 30 minutes. In highly developed sections, the inlet time may be as low as 3minutes. The time of flow is determined by the length of the drain and the velocity of flowin the drain. It is to be computed for each length of drain to be designed.

8

1.3 COEFFICIENT OF RUNOFF

The portion of rainfall which finds its way to the drain, is dependent on theimperviousness and the shape of tributary area apart from the duration of storm.

a) ImperviousnessThe percent imperviousness of the drainage area can be obtained from therecords of a particular district. In the absence of such data, the following mayserve as a guide:

Type of area Percentage of Imperviousness

Circular-8 Guidelines for Drainage sector Pagel50fl7

Commercial and Industrial area 70 to 90

Residential Areas:

i)ii)

High densityLow density

60 to 7535 to 60

Parks and undeveloped areas 10 to 20

The weighted average imperviousness of drainage basin for the flowconcentrating at a point may be estimated as

= A1 C1 + A2 C2 / A1 + A2 +

A1, A2 = drainage area tributary to the section under consideration

c1, C2 = imperviousness of the respective areas and

c = weighted average imperviousness of the total drainage basin

8b) Tributary Area

For each length of storm sewer, the drainage area should be indicated clearly onthe map and measured. The boundaries of each tributary are dependent ontopography, land use, nature of development and shape of the drainage basins.The incremental area may be indicated separately on the compilation sheet andthe total area computed.

c) Duration of StormContinuously long light rain saturates the soil and produces high coefficient thanthat due to heavy but intermittent rain in the same area because of the lessersaturation in the latter case. Runoff from an area is significantly influenced by thesaturation of the surface nearest the point of concentration, rather than the flowfrom the distant area. The runoff coefficient of a larger area has to be adjusted bydividing the area into zones of concentration and by suitably decreasing thecoefficient with the distance of the zones.

8d) Computation of Runoff Coefficient

The weighted average runoff coefficients for rectangular areas of length fourtimes the width as well as for sector shaped areas with varying percentages ofimpervious surface for different times of concentration are given in Table 1.3.Although these are applicable to particular shapes of areas, they also apply in ageneral way to the areas which are usually encountered in practice. Errors due todifference in shape of drainage are within the limits of accuracy of the rationalmethod and of the assumptions on which it is based.

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TABLE 1.3

Duration, t,minutes

10 20 30 45 60 75 90 100 120 135 150 180

1) Sector

concentratingin stated time

(a)Impervious

525 588 .642 700 .740 771 795 .813 .828 840 850 865

(b) 60%

Impervious.365 427 .477 531 569 598 622 .641 .656 .670 682 701

(c) 40%Impervious8 .285 346 .395 .446 482 512 .535 554 571 585 597 .618

(d) Pervious 125 185 .230 .277 .312 .330 .362 .382 .399 .414 429 454

2) Rectangle(length = 4 x

width)concentratingin stated time

(a)Impervious

.550 .648 .711 .768 808 .837 .856 .869 .879 887 892 .903

(b) 50%Impervious

350 442 .449 551 590 .618 .639 .657 671 .683 694 713

(c) 30%Impervious

.269 .360 414 464 502 530 552 572 .588 .601 614 638

8(d) Pervious 149 .236 .287 334 .371 398 .422 445 463 .479 .495 .522

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